Nanometer precision metrology of submicron Cu/SiO2 interconnects using fluorescence and transmission x-ray microscopy

We used hard x-ray fluorescence and soft x-ray transmission microscopy to quantitatively measure “in situ” Cu/SiO2 interconnect dimensions down to 0.3 μm dimensions. We describe methods and analysis techniques for measuring submicron linewidths, lengths, and thicknesses with accuracies of 30–60 nm precision. The dimensions and shape of submicron Cu vias, W lines, and a 20 nm Ta liner and an electromigration defect (void) were determined by these methods. These nondestructive techniques promise to be useful for nanometer precision metrology studies of a variety of materials systems.